The present invention relates to a characterization (here, a characterization signifies to evaluate whether a shape for achieving a desired function is constituted) of a tip of a diamond stylus for working of an apparatus compounded with an atomic force microscope and a scanning electron microscope and additional working of a diamond stylus and removal of a working chip adhered to the stylus.
In accordance with progress of miniaturization of a semiconductor integrated circuit, also a pattern on a photo mask constituting an original blank of transcribing the pattern has been progressed. A photo mask is an original blank, and therefore, when there is a defect, the defect is fabricated in all of objects to be transcribed, and therefore, the photo mask is requested to be free of a defect. The defect is inevitably brought about in view of a mask working process, and therefore, the defect is corrected by using a laser. However, when the pattern is miniaturized, also the defect to be corrected becomes small, the laser cannot deal with such a small defect, and therefore, in recent times, a correction using a focused ion beam (FIB) has been used as a standard. An opaque defect and a clear defect are corrected by a gas-assisted etching of FIB or an FIB-CVD light shielding film. Also an FIB defect correcting apparatus reaches a limit because in accordance with the progress of the miniaturization, an allowable range of an image resolution or a reduction in a transmittance by gallium injection by short wavelength formation of a reduction projection exposure apparatus becomes severe and a technology of overcoming the limit has been requested. In order to avoid the reduction in the transmittance by higher resolution formation and gallium injection derived from FIB, a defect correction apparatus (K. Edinger, H. Becht, J. Bihr, V. Boegli, M. Budach, T. Hofmann, H. P. Coops, P. Kuschnerus, J. Oster, P. Spies and B. Weyrauch, J. Vac. Sci. Technol. B22 2902-2906 (2004)) using an electron beam, or a technology of physically removing an opaque defect by a stylus harder than a material to be worked (defect) (scratching) by using an atomic force microscope (AFM) has been reduced into practice (Y. Morikawa, H. Kokubo, M. Nishiguchi, N. Hayashi, R. White, R. Bozak, and L. Terrill, Proc. of SPIE 5130 520-527 (2003)). Although a clear defect can easily be corrected by a defect correcting apparatus using an electron beam, there is present a case in which an opaque defect is difficult to be corrected practically. On the other hand, in a physical removing apparatus using an atomic force microscope, although an opaque defect can be corrected, a clear defect cannot be corrected in view of a principle thereof.
A physical removing apparatus using an atomic force microscope uses one obtained by sharpening diamond as a working stylus. Even a removing capability of diamond is reduced owing to a wear of a stylus or a working chip adhered to the stylus in correcting to remove an opaque defect. A characterization of a tip of a working stylus becomes important in excellently removing an opaque defect with a reproducibility. According to an apparatus compounded with a defect correcting apparatus using an electron beam and a physical defect removing apparatus using an atomic force microscope, also an in-situ characterization of a front end of a working stylus by an electron beam can be carried out in view of a principle thereof.
According to a working apparatus compounded with an atomic force microscope and a scanning electron microscope, when a sharpened tip of a stylus is observed by the scanning electron microscope, since a conductivity of diamond constituting a material of the stylus is deficient, observation is carried out normally by an acceleration voltage equal to or lower than 2 kV such that charge up is not brought about. However, high resolution observation is difficult by such an acceleration voltage so far as a working distance is shortened, and a special stylus attaching jig needs to be prepared. Further, in a case of shortening the working distance, when detection is carried out by a secondary electron detector normally provided upward from an object lens, a charged-up image is liable to be brought about, in order to avoid charge up, the acceleration voltage needs to be further lowered, and it is difficult to achieve a high resolution image under a condition without charge up. Although charge up is alleviated when the detector is provided downward from the object lens, only an image having a low S/N is achieved when the working distance is short. Further, when a defect correcting apparatus using an electron beam and a physical removing apparatus using AFM are compounded, there poses a problem that a restriction in a position of the secondary electron detector or the working distance is severe and it is also difficult to apply a background art observing method.
In recent times, there has been developed a scanning microscope technology of an environment control type capable of carrying out high resolution observation even under low vacuum of 100 through 1000 Pa, by irradiating an electron beam while making water or nitrogen flow at inside of a vacuum chamber, even high resolution observation of an insulating substance of a ceramic or a living body sample is made to be able to be carried out by a high acceleration voltage without charge up (for example, Nonpatent A. Liukkonen, Scanning 19 411(1997)).
Further, an electron beam can carry out etching by a chemical effect by selecting an assist etching gas. It is known that diamond can be worked by irradiating the electron beam under a hydrogen or oxygen atmosphere (J. Taniguchi, I. Miyamamoto, N. Ohno, and S. Honda, Jpn. J. Appl. Phys. 35 6574-6578 (1996) and J. Taniguchi, I. Miyamamoto, N. Ohno, K. Kanatani, M. Komuro and S. Honda, Jpn. J. Appl. Phys. 36 7691-7695 (1997)). Even under a steam atmosphere, a removing effect similar to that of hydrogen or oxygen can be expected. Further, it is known that even Cr or MoSi or glass can be removed by irradiating the electron beam under an atmosphere of xenon fluoride.
It is a problem of the invention that in an apparatus compounded with a defect correcting apparatus using an electron beam and a physical defect removing apparatus using an atomic force microscope which can perform a clear defect correction and an opaque defect correction in the same apparatus, by utilizing the above-described characteristic of the electron beam in observation and working, a diamond stylus for working of an atomic force microscope is observed with high resolution, when the stylus is deteriorated or adhered with working chip, a damage on the diamond stylus is reduced, the diamond stylus is worked to be sharpened, or a dirt is removed therefrom.